Automatic draft controller



E. Z.BURNS AND a. KEILLER.

AUTOMATIC DRAFT CONTROLLER. APPLICATION FILED OCT. 8, 1920.

1,433,446 Patented Oct. 24, 1922.

3 SHEETSSHEE1 l.

E. Z. BURNS AND' G. KEILLER.

AUTOMATIC DRAFT CONTROLLER.

APP'UCATION FILED OCT. 8. 1920.

1,433,446. Patented s SHEETS-SHEEI 2.

Ira awn 6 414. 5 W law b E. Z.'BURNS AND G. KEILLER.

AUTOMATIC DRAFT CONTROLLER.

APPLICATION FILED ocT. 8. 1920.

Patented Oct. 24, 1922.

3 SHEETSSHE ET 3.

Patented Oct. 24, 1922.

PATENT OFFICE.

ELIER Z. BURNS, OF MADISON, NEW J E YORK,

BSEY, AND GEORGE KEILLER, OF NEW AUTOMATIC DRAFT CONTROLLER.

Application filed October 8,

To all whom. it may concem:

Be it known that we, ELMER Z. BURNS, a citizen of the United States,residing in Madison, county of Morris, State of New Jersey, and GEORGEKEILLER, a citizen of the United States, residing in New York, countyand State of New York, have invented a certain Improvement in AutomaticDraft Controllers, of which the following is a specification.

Our present invention relates principally to means whereby the supply ofair to the furnace of a steam generator may be automatically governed bychanges in the pressure of the steam generated, for the purpose ofmaintaining such pressure as nearly constant as possible withinpredetermined limits, although also applicable to water gates or otherpower modifiers.

. The principal object of the invention s to provide a simple andrelatively inexpensive apparatus for the purpose named. which shall beeasy to assemble and to keep in order, and adaptable to plants alreadyconstructed, without any material or expensive changes. Our improvedapparatus takes up very little room, is very flexible and lends itselfto a great variety of embodiments or modifications.

. By way of example, we have illustrated a preferred form of ourapparatus in the accompanying drawings wherein Figure 1 is adiagrammatic view showing the general mechan cal arrangement of theentire system, Figure 1 is a modification of the draft controlling meansshown in Figure 1, Figure 2 is a diagram of the electrical features ofthe apparatus, Figure 3'is an isometric 'view of the initial contactmaking and'c'rcuit reversing apparatus, Figure 4 is a plan view ofcertain details of the circuit reversing'switch and'Figure 5 is a planView of the switch group shown at the top of Figure 3.

In Figure L the boiler whose draft is to be controlled is indicated at10, the stack being indicated at 11. Our invention relates to automaticmotive means, controlled by variations in steam pressure. temperature,speed or the like, which means may be switch.

1920. Serial No. 415,510.

applied to the appropriate operation of a variety of draft modifyingdevices or other regulators. without' departing from the scope of theinvention. As an illustration of the universal nature of the invention,we have shown in Figure 1 two alternative. forms of draft modifierseither of which can be operated by the motive means which forms thesubject matter of our invention.

In the preferred form shown the immediate motive agent is thereciprocating rod 12, although it is obvious that other forms of movableimpelling device may be used as equivalents. The rod 12 isscrew-threaded and carries a sleeve 13 at one end which slides upon aguide 14, while the other end of the rod slides in guides 15 betweenwhich is placed a revoluble nut 16, provided with a worm-wheel 17.driven by a worm 18 on the armature shaft of an electric motor 19. Asthis nut is revolved in one direction or the other, the impelling rod 12will move to the right or left in Figure 1.

In one alternative form shown in. Figures 1 and 1 the rod 12is'mechanically connected with the movable member of a switch or circuitcontroller 20, by means of which the operation of the electric blower 21is regulated. This blower supplies .forced draft to the furnace of theboiler 10 through the ipe 22. Y

In the other form (shown in Figure 1*) connection is made preferablythrough a stiff spring 22' with a swinging damper 23 in the outgoingflue 24, whereby the draft is modified in a well known manner.

The operation of the electric motor 19 which actuates the impellingdevice 12 is accomplished by a main lever whose movements are madedependent upon changes in the steam pressure in the boiler 10. In thepreferred form shown, this lever controls a series of initial circuitmakeis and reversing The main lever 25 is fulcrumed'at 26 and an arm 27on this lever has a pin 28 which projects through a slot 29 at the'upperend of the bar 30, which is carried by the lever 31, fulcrumed at32.This lever 31 is held in approximately the position indicated by a knifeedge 33 which is carried by the flexible diaphragm of a pressure gauge34, connected by the pipe 35 with the boiler 10; and is therefore alwayssubjected to the steam pressure present at any time within said boiler.w

The steam pressure, tending to lift the lever 31 is balanced by a weight36 onthe arm 37, fulcrumed at 38, and by a properly calibrated spring39. This latter supplies the element of variable tension necessary toregulate the balanced movements of the lever 31 between the upper andlower stops 40 and 41. lit will be clear from the foregomg that anincrease in steam pressure will produce a swinging movement of theswitch lever 25 clockwise through the eccentric pin connection 28, bar30 and lever 31, while a decrease in pressure will produce a contraryswing in the lever 25.

As shown in Figures 1 and 3, the main lever 25 controls a series of fiveinitial circuit makers, held in a casing 42. One of these and parts ofothers are shown complete in Figure 3. The others are all like the oneshown and are omitted for the sake of clearness.

Each intial circuit marker comprises a horizontal conducting shaft 43,turning verv easily in its bearings, and held normally balanced in theposition shown by the weight of the conducting plate 44 suspendedbeneath it, and the fact that its pivotal sup ports are located aboveits geometrical axis. This plate makes continual contact with themercury mass 45. Near the front, the shaft 43 is provided with atransverse curved wire 46, normally out of circuit, but which makescontact at one end or the other with the mercury mass 47 whenever theshaft 43 1s revolved one way or the other. These mercury masses or tanks47 are arranged in staggered relation to conserve lengthwise space, asshown in Figure 5.

This movement, whereby contact is made at 47 1s produced by the finger48 striking one side or the other of the pin 49 which pro ectsnormallyupright from the shaft 43. In order to insure completion of theoperation called for by a given movement of the lever 25, as well as toprevent breaking of the full working current at the mercury surfaces(causing destructive arcs) we prefer to associate the series of initialcir cuit makers with a corresponding series of electromagnetic relays,shown at 50 in Figure 1 and fully described hereinafter.

The direction of rotation of the motor 19 s determined by the reversingswitch. which is preferably constructed and operated as follows- IWithin a casing 51 at the bottom of the lever 25 is placed a lightlyturning shaft 52, similar to the shaft 43, but made of insulatmgmaterial. instead of metal. 'Underthis masses 58 and 59 respectively,when the shaft 52 is tilted one way or the other. This shaft tends toreturn to normal under the action.

of the light spring 59'.

At its forward end, the shaft 52 is similarly provided with the metalplate 60 having a depending portion 61 dipping constantly into themercury 62, while the two wires 63 and 64, may dip into mercury masses65 or 66, according to which way the shaft 52 is tilted.

The tilting one way or the other of the shaft 52 is accompli-shed by theaction of any one of the five pins 67 on the arc 68, carried by thelever 25, when it presses one way or the other on the normally uprightpin 69, fixed to the shaft 52.

it will be understood that the parts are so arranged and proportionedthat the beginning and ending of contact between the finger 48 and anyone pin 49 are coincident with the beginning and ending of contactbetween the pin 69 and a corresponding pin 67 on the are 68.

In order that when contact is once made in the reversing switch it maycertainly be preserved until completion of the desired automaticoperation. a piece of steel or iron 70 is fixed under the, middle of-theshaft 52 and is presented to the contiguous pole of one or the other ofthe electromagnets 71, 7 2. hereinafter described.

From the above it will be clear that the tilting of any of the series ofinitial circuit makers in either'"direction will cause electricalconnection between the two mercury masses belonging toy that switch. Onthe other hand the tilting of the reversing switch clockwise willconnect the mass 62 with the mass 66 and the mass 55 with the mass 59;While counter-clock movement will connect 62 with 65 and 55 with 58.

While the movement of the impelling means is initiated, by means thusfar described, any such movement is automatically limited, and theapparatus is brought to rest, preferably bythe following means.

Along the path of movement of the rod 12 is located a series ofcircuit-opening switches. As shown in Figure 1, there are seven ofthese, of which five correspond to the .five initial circuit makers andthe two at opposite ends of the series supply limiting means, wherebyexcessive travel of the impelling means in either direction is prevented.

The circuit-opening switches are numhered from 73 to 79, and are carriedupon a bar or shelf 60, upon. which each switch position by screws asshown. The roller 81 carried by and moving with the rod 12,

is adapted to open any switch under which it comes during its travel,and in whichever direction said roller is moving.

It has been found in practice that the degree of change in position ofcertain forms of draft controller (for instance a damper 23) is not thesame for all actual positions. The amount of movement which should beimparted to such a controller in a given position is determined byexperiment, having in view particularly the maintenance of a maximum (0output. ()nce having determined this, the switches 73 to 77 can beadjusted so that they may act to interrupt the movements of theimpelling device or rod 12 at appropriate positions of the draftcontroller. This adjustability is an important feature of the invention.

The operation of the entire apparatus may now be described, withreference to Figure 2, wherein are shown the electric circuits involved.\Ve shall describe the operation with respect to a single set ofcircuits only, as What is said regarding one position is true of all.

It is assumed that a lowering of steam pressure has caused the lever 25to swing anti-clockwise, thus tilting the shaft of the initial circuitmaker 82, and producing, therefore, a clockwise movement of thereversing switch shaft 52.

The field-magnet coils 83 of the motor 19 are, as shown, permanentlyconnected with the mains 84, 85. Upon closure of the initial circuit at82, the motor armature 86 will be energized as follows- From 8 1,through 79, by magnet 71', mercury 66, 62, armature 86 (right to left)wire 87, starting resistance, 88, wire 89, temporary coil 90 on one ofthe series 50 of relay magnets, wire 91, switch 82, wire 92,aircuit-opening switch 76, wire 93, mercury 59, wire 94, mercury 65,wire 95 to main 85.

This will cause the rod 12 to move in the direction of the arrow inFigure 2, cans ing the damper to open more widely, or an equivalenteffect to be produced in any other type of draft controller, that may beadopted. I

Thelow resistance current thus set to work will operate through therelay 90 to close the switch 96, which will short-cir-.

roller 81 coming under the switch 76.

In Figure 2 the swltch is shown open,

as left at the end of a prior movement of the ap aratus; It is, ofcourse, understood that afl of the switches 73 to 79 are automatic andclose of themselves when freed from the pressure of the roller 81.

As is apparent fromFigure 2, any movement of the main lever 25.clockwise, due

to increase of steamv pressure, will set up a current through thearmature 86 from left.

to right in Figure 2, thus reversing the motor and producing a limitedmovement to partly close the damper (or to produce an equivalentdraft-controlling effect.) For instance, assuming the operation lastdescribed to have been completed, .the lever 25 being to the left of theswitch 82 and the roller 81 having moved to the right in Figure 2 farenough to open the switch 76.

Now, if the steam. pressure increases and moves the lever clockwise (andtherefore the shaft 52 anti-clockwise) this lever 25 will move past theswitch 82 which is now dead, owing to switch 76 being open, until thenext switch to the right of 82 will be closed, when the followingcircuit will be established.

From 84, through the limiting switch 73 to magnet 72, mercury 58, shaft52, mercury 55, wire 93, switch 75, switch just closed to the right of82, magnet 90 directly above switch 75, wire 89, resistance 88, wire 87,armature 86 (left to right) mercury 62,

mercury 65, wire 95, and out at 8 5.

It will be seen that our invention provides an automatic motivemechanism whereby ing or closing, and it is variable in extent,

being automatically limited at the end of one, two or more stepsaccording to circumstances. In addition to these advantages, theadjustability of the circuit-openers along their support makes itpossible to operate by steps of adjustable length, calculated indifferent positions to correspond to movements of maximum efficiency foreach position, as determined by experiment.

' It is a further advantage of our invention that, by using the relays50 andthe switchretaining magnets 71 and 72, the definite completion ofa particular'step is assured despite possible irregularities in themovement of the main lever 25, or its equivalent, due to steam surgingor other accidental causes.

While our invention is principally useful in connection with systemswherein the draft control ismade dependent upon variations in steampressure, we do not confine ourselves to this field, since it is obviousthat the main lever 25, or its equivalent, may be actuated by agencies,responsive to other changes than those of pressure, as for instance, tochanges of temperature or changes of speed. Consequently the expressionapparatus of the character described as used in our claims is to beunderstood to refer to any automatic motive mechanism for the operationof shaft controllers, whatever the nature of the changes upon whichoperation depends.

Various changes or modifications may be made 1n the form and arrangementof our apparatus without departing from the scopeof ourinvention and wedo not limit ourselves to the details herein shown and described.

What we .clain'ris 1. ln apparatus for automatic draft con trol, a draftregulator, impelling means therefor, a reversible electric motor fordriving said means in one direction or the other, a series of initialcircuit closing switches. a switch operating device movable along saidseries in either direction adapted to operate said switches to closecircuit therethrough and through a part of said motor in whicheverdirection said device moves, pressure motive means for operating saidswitch operating device, and a source of pressure dependent upon thedraft regulated for actuating said pressure motive means.

2. Apparatus of the character set forth in claim 1 hereof in combinationwith a .re-

versing switch for said motor operated by said switch operating device.

3. In apparatus as set forth in claim 1 hereof, a high resistanceClIClllt COIIIPIlSlIlg branches each including a relay magnet coil andone of said initial circuit makers, and low resistance permanent branchcircuits each including a relay coil and a magnetic switch operated bysaid relay coils successively, said permanent branch circuits beingarranged in ashort circuit around said initial circuit makers to preventarcing, substantially as described.

4. In apparatus for automatic draft control. a draft regulator,impelling means therefor, a motor for driving the same in either of twodirections, vcontrolling means for causing step by step movement of saidmotor in either direction, a pressure motive mechanism capable of'actingin any position of the impelling means to operate said controllng means,and a source of pressure dependent upon the draft regulated foractuating said pressure motive mechanism.

5. In apparatus of the character described an impelling device, step bystep motive means for actuating the same and automatic interrupters forsaid motive means placed in a series along the path of movement of saidimpelling means and adapted to be opperated thereby, said interrupter-sbeing adjustable as to position, whereby the different steps may bevaried in extent at will.

6. Apparatus of the character set forth in for fixing the switches indifferent positions along said support at will.

9. In apparatus of the class described, an actuating electric motor, atilting switch for reversing the same, electromagnetic means in circuitwith said motor for holding the tilting element of said switch in oneextreme position or the other, a revoluble shaft for operating thetilting switch, an electro-magnet .on each side thereof adapted to bebrought automatically in circuit with said switch, and an armature undersaid shaft adapted to be brought opposite the pole on one or the otherof said electro-magnets when said shaft is tilted to operate the switch.

It). Apparatus of the character set forth in claim 1 hereof wherein eachinitial circuit closer comprises a light balanced revoluble shaftcarrying circuit closing means and a normally upright pin, and whereinthe main lever is adapted to sweep over said pins in either of twodirections so as to depress them sufficiently to allow the main lever tomove onward.

11. Apparatus of the character set forth in claim 1 hereof-wherein eachinitial circuit closer comprises .two mercury masses, a revoluble shaftmounted over the same, a depending conductive member on said shaftdipping constantly into one of said mercury masses, and a secondconductive member on the shaft adapted to dip one ,end or the other intothe other mercury mass when said shaft is tilted. I

12. In apparatus of. the character described, impelling means, areversible electric motor for driving the same, a series of initialcircuit closers for said motor normally in open circuit position and aswinging circuit reversing switch for said motor normally in openposition; in combination with a main lever fulcrumed between thereversing switch and circuit closers, said lever being adapted tooperate said circuit closers successively by impact at one end of thelever,

and being provided with a, number of pins at its other end forsuccessive operation of said reversing switch.

13; In apparatus of the character set forth incleim 12 hereof, a fingerat one end of the main lever for operating the circuit closerssuccessively and an are at the opposite end havin pins adapted tooperate the reversin 'switc co-incidently With each operation 0 acircuit maker.

In testimony whereof We have hereto set our hands on this 5th day ofOctober, 1920.

ELMER Z. BURNS, GEORGE KEILLER

